/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.servlet.tags.form;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import javax.servlet.jsp.JspException;

import org.springframework.beans.BeanWrapper;
import org.springframework.beans.PropertyAccessorFactory;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * Abstract base class to provide common methods for implementing
 * databinding-aware JSP tags for rendering <i>multiple</i>
 * HTML '{@code input}' elements with a '{@code type}'
 * of '{@code checkbox}' or '{@code radio}'.
 *
 * @author Juergen Hoeller
 * @author Scott Andrews
 * @since 2.5.2
 */
@SuppressWarnings("serial")
public abstract class AbstractMultiCheckedElementTag extends AbstractCheckedElementTag {

    /**
     * The HTML '{@code span}' tag.
     */
    private static final String SPAN_TAG = "span";


    /**
     * The {@link java.util.Collection}, {@link java.util.Map} or array of objects
     * used to generate the '{@code input type="checkbox/radio"}' tags.
     */
    private Object items;

    /**
     * The name of the property mapped to the '{@code value}' attribute
     * of the '{@code input type="checkbox/radio"}' tag.
     */
    private String itemValue;

    /**
     * The value to be displayed as part of the '{@code input type="checkbox/radio"}' tag.
     */
    private String itemLabel;

    /**
     * The HTML element used to enclose the '{@code input type="checkbox/radio"}' tag.
     */
    private String element = SPAN_TAG;

    /**
     * Delimiter to use between each '{@code input type="checkbox/radio"}' tags.
     */
    private String delimiter;


    /**
     * Set the {@link java.util.Collection}, {@link java.util.Map} or array of objects
     * used to generate the '{@code input type="checkbox/radio"}' tags.
     * <p>Typically a runtime expression.
     *
     * @param items said items
     */
    public void setItems(Object items) {
        Assert.notNull(items, "'items' must not be null");
        this.items = items;
    }

    /**
     * Get the {@link java.util.Collection}, {@link java.util.Map} or array of objects
     * used to generate the '{@code input type="checkbox/radio"}' tags.
     */
    protected Object getItems() {
        return this.items;
    }

    /**
     * Set the name of the property mapped to the '{@code value}' attribute
     * of the '{@code input type="checkbox/radio"}' tag.
     * <p>May be a runtime expression.
     */
    public void setItemValue(String itemValue) {
        Assert.hasText(itemValue, "'itemValue' must not be empty");
        this.itemValue = itemValue;
    }

    /**
     * Get the name of the property mapped to the '{@code value}' attribute
     * of the '{@code input type="checkbox/radio"}' tag.
     */
    protected String getItemValue() {
        return this.itemValue;
    }

    /**
     * Set the value to be displayed as part of the
     * '{@code input type="checkbox/radio"}' tag.
     * <p>May be a runtime expression.
     */
    public void setItemLabel(String itemLabel) {
        Assert.hasText(itemLabel, "'itemLabel' must not be empty");
        this.itemLabel = itemLabel;
    }

    /**
     * Get the value to be displayed as part of the
     * '{@code input type="checkbox/radio"}' tag.
     */
    protected String getItemLabel() {
        return this.itemLabel;
    }

    /**
     * Set the delimiter to be used between each
     * '{@code input type="checkbox/radio"}' tag.
     * <p>By default, there is <em>no</em> delimiter.
     */
    public void setDelimiter(String delimiter) {
        this.delimiter = delimiter;
    }

    /**
     * Return the delimiter to be used between each
     * '{@code input type="radio"}' tag.
     */
    public String getDelimiter() {
        return this.delimiter;
    }

    /**
     * Set the HTML element used to enclose the
     * '{@code input type="checkbox/radio"}' tag.
     * <p>Defaults to an HTML '{@code <span/>}' tag.
     */
    public void setElement(String element) {
        Assert.hasText(element, "'element' cannot be null or blank");
        this.element = element;
    }

    /**
     * Get the HTML element used to enclose
     * '{@code input type="checkbox/radio"}' tag.
     */
    public String getElement() {
        return this.element;
    }


    /**
     * Appends a counter to a specified id as well,
     * since we're dealing with multiple HTML elements.
     */
    @Override
    protected String resolveId() throws JspException {
        Object id = evaluate("id", getId());
        if (id != null) {
            String idString = id.toString();
            return (StringUtils.hasText(idString) ? TagIdGenerator.nextId(idString, this.pageContext) : null);
        }
        return autogenerateId();
    }

    /**
     * Renders the '{@code input type="radio"}' element with the configured
     * {@link #setItems(Object)} values. Marks the element as checked if the
     * value matches the bound value.
     */
    @Override
    @SuppressWarnings("rawtypes")
    protected int writeTagContent(TagWriter tagWriter) throws JspException {
        Object items = getItems();
        Object itemsObject = (items instanceof String ? evaluate("items", items) : items);

        String itemValue = getItemValue();
        String itemLabel = getItemLabel();
        String valueProperty =
                (itemValue != null ? ObjectUtils.getDisplayString(evaluate("itemValue", itemValue)) : null);
        String labelProperty =
                (itemLabel != null ? ObjectUtils.getDisplayString(evaluate("itemLabel", itemLabel)) : null);

        Class<?> boundType = getBindStatus().getValueType();
        if (itemsObject == null && boundType != null && boundType.isEnum()) {
            itemsObject = boundType.getEnumConstants();
        }

        if (itemsObject == null) {
            throw new IllegalArgumentException("Attribute 'items' is required and must be a Collection, an Array or a Map");
        }

        if (itemsObject.getClass().isArray()) {
            Object[] itemsArray = (Object[]) itemsObject;
            for (int i = 0; i < itemsArray.length; i++) {
                Object item = itemsArray[i];
                writeObjectEntry(tagWriter, valueProperty, labelProperty, item, i);
            }
        } else if (itemsObject instanceof Collection) {
            final Collection<?> optionCollection = (Collection<?>) itemsObject;
            int itemIndex = 0;
            for (Iterator<?> it = optionCollection.iterator(); it.hasNext(); itemIndex++) {
                Object item = it.next();
                writeObjectEntry(tagWriter, valueProperty, labelProperty, item, itemIndex);
            }
        } else if (itemsObject instanceof Map) {
            final Map<?, ?> optionMap = (Map<?, ?>) itemsObject;
            int itemIndex = 0;
            for (Iterator it = optionMap.entrySet().iterator(); it.hasNext(); itemIndex++) {
                Map.Entry entry = (Map.Entry) it.next();
                writeMapEntry(tagWriter, valueProperty, labelProperty, entry, itemIndex);
            }
        } else {
            throw new IllegalArgumentException("Attribute 'items' must be an array, a Collection or a Map");
        }

        return SKIP_BODY;
    }

    private void writeObjectEntry(TagWriter tagWriter, String valueProperty,
                                  String labelProperty, Object item, int itemIndex) throws JspException {

        BeanWrapper wrapper = PropertyAccessorFactory.forBeanPropertyAccess(item);
        Object renderValue;
        if (valueProperty != null) {
            renderValue = wrapper.getPropertyValue(valueProperty);
        } else if (item instanceof Enum) {
            renderValue = ((Enum<?>) item).name();
        } else {
            renderValue = item;
        }
        Object renderLabel = (labelProperty != null ? wrapper.getPropertyValue(labelProperty) : item);
        writeElementTag(tagWriter, item, renderValue, renderLabel, itemIndex);
    }

    private void writeMapEntry(TagWriter tagWriter, String valueProperty,
                               String labelProperty, Map.Entry<?, ?> entry, int itemIndex) throws JspException {

        Object mapKey = entry.getKey();
        Object mapValue = entry.getValue();
        BeanWrapper mapKeyWrapper = PropertyAccessorFactory.forBeanPropertyAccess(mapKey);
        BeanWrapper mapValueWrapper = PropertyAccessorFactory.forBeanPropertyAccess(mapValue);
        Object renderValue = (valueProperty != null ?
                mapKeyWrapper.getPropertyValue(valueProperty) : mapKey.toString());
        Object renderLabel = (labelProperty != null ?
                mapValueWrapper.getPropertyValue(labelProperty) : mapValue.toString());
        writeElementTag(tagWriter, mapKey, renderValue, renderLabel, itemIndex);
    }

    private void writeElementTag(TagWriter tagWriter, Object item, Object value, Object label, int itemIndex)
            throws JspException {

        tagWriter.startTag(getElement());
        if (itemIndex > 0) {
            Object resolvedDelimiter = evaluate("delimiter", getDelimiter());
            if (resolvedDelimiter != null) {
                tagWriter.appendValue(resolvedDelimiter.toString());
            }
        }
        tagWriter.startTag("input");
        String id = resolveId();
        writeOptionalAttribute(tagWriter, "id", id);
        writeOptionalAttribute(tagWriter, "name", getName());
        writeOptionalAttributes(tagWriter);
        tagWriter.writeAttribute("type", getInputType());
        renderFromValue(item, value, tagWriter);
        tagWriter.endTag();
        tagWriter.startTag("label");
        tagWriter.writeAttribute("for", id);
        tagWriter.appendValue(convertToDisplayString(label));
        tagWriter.endTag();
        tagWriter.endTag();
    }

}
